Psoriasis - Symptoms, Types, Causes, Prevention and Treatment

Psoriasis definition

Psoriasis, an autoimmune disorder, is a chronic (long-lasting), multisystem, proliferative (multiplying in number rapidly) inflammatory condition of the skin that mainly involves skin and joints.

Psoriasis is common in all age groups, from children to adolescents. It is seen as erythematous plaques covered with silvery scales, mainly over the extensor surfaces, lumbosacral region, and scalp. The disorder can also affect the eyes and joints. Some people with psoriasis may experience itching or soreness. Sometimes, the signs and symptoms of psoriasis will flare up for a few weeks or months; then, they will subside or go into remission (decrease in symptoms).

Scientists have not fully understood the causes of psoriasis, but immunological, genetic, and environmental factors, including diet, may cause it. The distribution and appearance of lesions determine the diagnosis of psoriasis, and the type and severity of the disease determine the treatment. Dermatologists with specialized knowledge and skills in treating and caring for skin, hair, and nail conditions are the essential healthcare personnel who effectively handle psoriasis cases.

Psoriasis meaning

The term psoriasis was first introduced by Greek physician Galen (133-200), meaning an itchy, exfoliative condition of the eyelids and scrotum, similar to the modern definition of seborrheic dermatitis, that was treated with a viper’s broth.

Psoriasis prevalence

Prevalence of psoriasis in the World

The prevalence of psoriasis among adults ranges from 0.91 to 8.5%, while in children, it varies from 0.0 to 2.1%, according to estimations of epidemiological data on psoriatic illness. Around 2-3% of people worldwide suffer from psoriasis, with prevalence rates as high as 8–11% in several Northern European nations. In 2017, there were 811 cases of psoriasis per 100,000 people worldwide, or roughly 0.84% of the world's population, or 64.6 million people. From 92 instances per 100,000 in 1990 to 99 in 2017, the incidence of new cases rose. Asia and the Western Pacific areas had the lowest rates, while North America and Western Europe had the highest rates.

Prevalence of psoriasis in India

The frequency of adult psoriasis in India ranges from 0.44 to 2.8%. The majority of patients are in their third or fourth decade at the time of clinical manifestation, and it affects men twice as frequently as it does women.

Psoriasis types

While there are various types of psoriasis, the plaque form is the most prevalent and affects the scalp, limbs, and trunk. The following are the three main types of psoriasis:

• Plaque psoriasis
• Pustular psoriasis
• Generalized pustular psoriasis (GPP)
• Localized pustular psoriasis
• Acrodermatitis continua of hallopeau (ACH)
• Psoriatic arthritis
  

Plaque psoriasis

Plaque psoriasis is the most frequent form of psoriasis and occurs in 85%–90% of affected patients. It is identified by oval or irregularly shaped, sharply demarcated, red-raised plaques covered by silvery scales.

Although plaques can affect any part of the body, and most frequently it develops symmetrically in the elbows, knees, and hands' lower back, scalp, and extensor surfaces. Lesions can vary in size, giving rise to two distinct clinical sub-phenotypes: larger, solitary lesions or smaller, confluent patches. 

An additional classification considers the age of onset. Type I psoriasis manifests before age 40, is frequently linked to a well-known medical history, and has a strong correlation with the HLA-Cw0602 variant. In contrast, type II psoriasis appears after age 40.

Pustular psoriasis

Pustular psoriasis most commonly present  in the form of aseptic pustules. It is further classified into three subgroups:

• Generalized pustular psoriasis (GPP): It has a large skin rash characterized by aseptic abscesses and includes a varied degree of fever as the acute beginning symptom and is later associated with general malaise, exhaustion, and other systemic symptoms. It can affect  population of any age and is more seen in women than in males.
• Localized pustular psoriasis: It is the most widespread type of pustular psoriasis and is termed palmoplantar pustulosis (PPP). Patients with pustular psoriasis may experience tiny skin blisters filled with pus. In cases of pustular psoriasis, it may affect body parts, including extremities, 
• Acrodermatitis continua of hallopeau (ACH): This unusual form of psoriasis affects the phalanges of the hands and feet; many blister crops fuse on the nail bed and matrix, generating pus streams that cause the nails to dystrophy (abnormal changes in the shape and color, and growth of the fingernails or toenails) and the affected digits to become anonychia (absence of nails).

Psoriatic arthritis

Psoriatic arthritis is an inflammatory muscular condition linked to psoriasis of the skin that can affect 20-30 % of individuals. It can affect different tissues such as synovium, bone, tendons, cartilage, and entheses (connective tissue between tendon or ligament and bone).

Psoriasis symptoms

The symptoms of psoriasis may change from one person to the other. Symptoms may flare up at specific periods, making people feel worse, and then subside at different times. Following are some of the common symptoms of psoriasis:

• Psoriasis plaques: Patches of thick, red skin associated with silvery-white scales, usually on the elbows, knees, scalp, trunk, palms, and soles of the feet, that are itchy or burned. 
• Nail abnormalities: Pitted, ridged, thick nails.
• Skin dryness and irritation: Dry, cracked skin that bleeds or itches, shedding of scales of skin.
• Sleep disturbances: Inadequate quality of sleep.
  

Some triggering factors can make psoriasis patients' symptoms worse. Knowing these factors may help avoid a flare-up. The following are some of the risk factors for psoriasis.

The risk factors for psoriasis are mainly divided into two groups one is extrinsic and the other intrinsic risk factors.

Extrinsic risk factors of psoriasis

• Infection: Psoriasis occurs after streptococcal and Staphylococcus (S.) aureus infection. Human immunodeficiency virus (HIV) is also a well-known risk factor associated with psoriasis.
• Air pollution: The rise in air pollution has had significant effects on human skin. Air contaminants, including cadmium, influence the etiology of psoriasis.
• Vaccination: Numerous studies demonstrated the link between influenza vaccination and psoriasis exacerbation. Vaccination against influenza may potentially cause psoriasis to develop. 
• Alcohol: Consumption of alcohol has been associated with an increased risk of psoriasis. Yet, a previous systematic research concluded that there wasn't enough information to say whether drinking alcohol was a risk factor.
• Smoking: A comprehensive review and meta-analysis found that people with psoriasis are more likely to smoke, either now or in the past. Smokers have an increased risk of developing psoriasis.

Intrinsic risk factors of psoriasis

• Obesity: The onset and aggravation of psoriasis are closely correlated with obesity. The prevalence and risk of obesity are much increased in psoriasis patients.
• Diabetes mellitus: A meta-analysis linked psoriasis to diabetes mellitus. Many other meta-analyses have also demonstrated a link between psoriasis and the risk of diabetes mellitus.
• Hypertension: A meta-analysis revealed a greater incidence and prevalence of hypertension among psoriasis patients.
• Mental stress: Most people agree that mental stress is a known cause of psoriasis, and people with psoriasis believe that mental stress exacerbates their illness.
• Dyslipidaemia: Patients with dyslipidaemia are more likely to have psoriasis; as psoriasis worsens, this incidence is predicted to increase.
  

Psoriasis causes

Though the exact cause of psoriasis is not known, skin cells that grow and shed excessively quickly are assumed to be the reason. Following are some of the known causes of psoriasis:



• Abnormal growth of the skin cells: In the skin's deepest layer, the body generates new skin cells. These skin cells ascend the skin's layers gradually until they reach the outermost layer; they decompose and fall off. Usually, this entire process takes three to four weeks, but it takes only 3-7 days in psoriasis patients. This leads to immature cells rapidly accumulating on the skin's surface, producing dry, crusty areas that are coated with scales.
• Immune system problems: T-cells normally travel through the body to detect and fight invading germs (like bacteria), but in psoriasis patients, they start to attack healthy skin cells by mistake, causing rapid production of new skin cells, thus triggering the immune system.
• Genetics: Although the specific role that heredity plays in psoriasis is unknown, psoriasis runs in families, so having a close family with the condition may increase the risk of developing psoriasis.